1. Field of the Invention
The present invention relates mainly to a stroboscope circuit and, more particularly, to those having a charging capability of a main capacitor which discharges an electronic discharge lamp for stroboscopic flashlight illuminations during photographing by use of a film camera.
2. Brief Description of the Prior Art
FIG. 4 is a view showing main parts of a conventional stroboscope circuit. In the figure, a numerical character 1 stands for a stroboscope charging circuit charging up a capacitor C1 in use for flashlight illuminations, 3 stands for an input terminal VB receiving a synchronous signal (a timing signal) and 5 stands for a ground (GND) terminal.
When the synchronous signal VB (a voltage signal) is applied to aforesaid circuit, the stroboscope charging circuit 1 operates to supply a charging current to the capacitor C1 in use for flashlight illumination. A numerical value of this charging current is set up to be a certain specified value, for instance, some amperes (referred to as "A" hereinafter) to complete quickly a charge up operation of the capacitor C1.
FIG. 5 is a graph showing a time dependence of an input current supplied to aforesaid capacitor C1 in a conventional circuit. Herein an abscissa represents an elapsing time while an ordinate represents the input current I supplied to the capacitor C1. Namely, FIG. 5 indicates a waveform of the input current supplied to the capacitor C1 in the conventional charging circuit. It is clarified from FIG. 5 that the input current supplied to capacitor C1 is constant and saturates at a value of some A.
Because the charging current supplied to the capacitor has been specified at a higher value up to now to finish the charging operation earlier in the conventional stroboscope circuit as mentioned above, they have encountered with some problems wherein any other operations such as processing an exposure data concerning photographing, displaying a photographic image onto a liquid crystal device (referred to as "LCD" hereinafter) etc. cannot be performed during charging the capacitor.
Accordingly, the stroboscopic tubes have sometimes been subjected to a flashlight operation even at status wherein charging of the driving capacitor has not been completed yet.